Roadbed construction



Aug. 10 192 L. A. PERRY ROADBED CONSTRUCTION Filed Sept. 24, 1924 wfija Q2 /2 I j INVENTOR. Z. A. PERRY BY ATTORNEYS.

Patented Aug. 10, 1926.

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Application filed September 24%,-

The present invention relates to improvements in road bed construction and has for its particular object an arrangementof units or slabs in such a manner that the single units will stand a maximum ofpressure at any point before breaking. It has been.

ascertained by a series of tests and labora tory experiments as well as by actual use on. aroad bed that the hexagonal form of slab is better adapted for road bed construction than the square form, in View of the fact that when a slab of this character is loaded either in the center or at both ends, the maximum stress occurs along a central line, that is, along a line which offers maximum resistance to fracture.

This statement is further borne out by the following facts: The longest side of the hex agonal slab is less than that of one foursided figure of equal area whereby bending moments are minimized. The hexagonal slab covers an area equal to that of a square slab with about ten per cent less perimeter, which offers the further advantage ofeconomy in expansion joint material; thehexagon is the figure nearest approaching the circle which can be grouped with other figures of the same shape, and the circle. is naturally the most eliicient slab shape by virtue of ultimate compactness; in other words, any or all sections through it are maximum sections, and isolated corners are eliminated; the hexagonal grouping of concrete pavement is not diflicult to construct, approximately 70,000 square yards having been laid during this year under" the per sonal direction of the applicant.

The preferred form of my invention is illustrated in the accompanying drawing, in which Figure 1 shows a top plan View of my road bed, and Figure 2 the result of a series of tests made with hexagonal road bed'slabs and square slabs. I/Vhile I have shown only the preferred form of the invention, I wish to have it understood that various changes or modifications may be made within the scope of the claims hereto attached without departing from the spirit of the invention.

Referring first to Figure 2, it will be noted that seven hexagonal slabs 1 and seven square slabs 2 are shown, both of which sets of slabs have been subjected to loads applied at opposite corners, the loads gradu-, ally increasing up to the breaking point.

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It appears that in all the heriagonal slabs fracture occurred substantially along a center line 8, while square slabs subjected to loads'under similar conditions broke near the corners as shown at i, and in practically all of the instances developed two breaks instead of one break, both breaks being along lines considerably shorter turn those of the breaks invthe hexagonal slabs.

The comparison of the weights required to effect the different breaks shows that it took considerably more weight to break the hexagonal slabs than it did to break the square slabs, the figures for the hexagonal slabsbeing 336, 248, 232, 280, 313, 280 and pounds respectively, while the corresponding figures for the square slabs were 158, 15-0, 232, 216, 184:, 232 and 216 pounds respectively, the average for the hexagonal group being substantially 279 pounds and that for the square group substantially 196 pounds.

In View of these experiments it seems that a road bed made of hexagonal slabs or panels would be far superior to a road bed made of square panels of the same thickness. My invention contemplates an arrangement such as shown in Figure 1, in which the panels 6 are of hexagonal form and preferably arranged in such a manner relative to the road bed as topresent transverse joints 7 arranged in staggered relation with similar transverse joints 8, While zigzag joints 9 connect the transverse joints.

rality of individual slabs arranged in parallel longitudinal and oblique rows, the pe ripheries of aid slabs having adjacent side portions disposed at an angle of 120 so that when the adjacent slabs of each row are arranged in approximate contact'with one another and in approximate contact with the slabs of an adjacent row, angularly disposed portions of the slabs in each row will extend into the angular spaces providedby angula-rly disposed peripheral portions of adjacent slabs inan adjacent row, each of said slabs having a diagonal length not less than the transverse distance be:

2. A concrete roadway having an intermediate portion comprising a plurality of; individual slabs arranged in parallel rows, each of said slabs being hexagonal in con-- tour and in approximate contact with oppositely disposed adjacent slabs, the marginal side portions of said roadway being made up of individualslabs, each'of which is of fractional hexagonal contour and disposed with one of its corners interposed between adjacent corners oi two adjacent hexagodegrees,

nal slabs in one of theadj acent intermediate i rows, each'of said hexagonal and fractional hexagonal slabs having an upper surface of not less than 120-square feet.

tween the traction wheels of a road vehicle.

3. A concrete" pavement slab "of the character described" defined by two edges of equal length arranged at an angle of 120 two edges joining thefree ends of the first two edges at: angles of 120 degrees and running parallel to one another and a fifth "edge arranged at right angles to the latter two edges the longest dimension of said slab being not less than the transverse tion wheels of a road vehlclei distance between oppositely disposed trac 

